Enhancing the operation of a gasoline engine

ABSTRACT

By incorporating a fluorinated aliphatic compound, more particularly a fluorinated aliphatic hydrocarbon, fluorinated aliphatic hydrocarbyl amine, or fluorinated aliphatic hydrocarbyl amine salt into a gasoline composition the distribution of the air/fuel mixture in the intake manifold of a multicylinder gasoline engine will be improved when that engine is run with the resulting blend, thereby increasing operating efficiency. The fluorinated compound has a total of about 8 to 30 carbon atoms, the total number of fluorine atoms that are attached to either or both of the carbon atoms that are the terminal carbon atom of an aliphatic chain and the carbon atom immediately adjacent thereto being at least three. Representative fluorinated compounds include perfluoro kerosene and perfluoro tributyl amine.

llnited States Patent Furlong et al.

ENHANCING THE OPERATION OF A GASOLINE ENGINE Inventors: Louis E. Furlong, Westfield;

Abraham A. Zimmerman, New Providence; Hugh F. Shannon, Scotch Plains, all of NJ.

Assignee: Esso Research and Engineering Company, Linden, NJ.

Filed: Sept. 1, 1971 Appl. No.: 177,162

[52] US. Cl 44/66, 44/71, 44/72, 44/79 [51] Int. Cl C10] 1/22 [58] Field of Search 44/79, 71, 72, 66

[56] References Cited UNITED STATES PATENTS 3,565,926 2/1971 Furey 44/71 3,269,948 8/1966 Furey 44/71 2,680,717 6/1954 Little, Jr. 44/71 2,764,603 9/1956 Ahlbrecht 44/71 2,933,382 4/1960 Fowkes 44/71 Primary ExaminerDaniel E. Wyman Assistant Examiner-Mrs. Y. H. Smith Attorney, Agent, or Firm-Leon Chasan [5 7 ABSTRACT By incorporating a fluorinated aliphatic compound, more particularly a fluorinated aliphatic hydrocarbon, fluorinated aliphatic hydrocarbyl amine, or fluorinated aliphatic hydrocarbyl amine salt into a gasoline composition the distribution of the air/fuel mixture in the intake manifold of a multicylinder gasoline engine will be improved when that engine is run with the resulting blend, thereby increasing operating efficiency. The fluorinated compound has a total of about 8 to 30'carbon atoms, the total number of fluorine atoms that are attached to either or both of the carbon atoms that are the terminal carbon atom of an aliphatic chain and the carbon atom immediately adjacent thereto being at least three. Representative fluorinated compounds include perfluoro kerosene and perfluoro tributyl amine.

6 Claims, No Drawings ENHANCING THE OPERATION OF A GASOLINE ENGINE BACKGROUND OF THE INVENTION This invention concerns an improved motor fuel composition and an improved method of operating an internal combustion engine. More particularly, the invention concerns incorporating into a motor fuel, such as gasoline, an additive combination that will modify the induction tract surfaces of an aspirated multicylinder internal combustion engine in such a way as to improve the geometric and time distribution of the fuel in the induction system of that engine.

In operating a gasoline engine, it is necessary to supply to the cylinders a mixture of gasoline and air in proper proportions. in most instances, this is accomplished by the use of a carburetor wherein the fuel is aspirated into a stream of moving air. In an aspirated multicylinder engine the mixture of air and fuel is distributed to the various cylinders through an intake manifold. One problem that arises in such a system is that the air/fuel ratio tends to vary from cylinder to cylinder, i.e., there is a geometric variation, some cylinders receiving a relatively rich mixture and others a relatively lean mixture. Similarly, variations in air/fuel ratio in particular cylinders of a multicylinder engine can vary with respect to time. Such variations cause an engine to accelerate and decelerate as frequently as once per second, even though an attempt is made to hold the vehicle under steady cruise conditions with a fixed position of the throttle. If the variation in air/fuel ratio with time becomes sufficiently severe, it feels to the automobile driver as if his car is being buffeted by winds.

Both the geometric variation in air/fuel ratio distribution and the variation with respect to time result in reduced operating efficiency, which shows up in at least two ways, one being a loss in fuel economy and another being uneven and reduced power. Accordingly, it is desirable to reduce such variations.

Gasolines used as motor fuels comprise a mixture of hydrocarbons of various boiling points. Thus, a gasoline can have an initial boiling point in the range of about 70 to 135F. and a final boiling point in the range of about 250 to 450F. The mixture of gasoline and air that leaves the carburetor and passes to the var ious cylinders through the intake manifold tends to deposit some of the higher boiling fractions in the form of a liquid film on the walls of the intake manifold. This liquid film is the main factor in poor fuel distribution in the engine. Accordingly, it is desirable to have the gasoline present as a vapor or spray in the air/fuel mixture to ensure greater engine operating efficiency.

DESCRIPTION OF THE INVENTION In accordance with the present invention it has been found that the distribution of the air/fuel mixture to the various cylinders of an aspirated multicylinder internal combustion engine can be improved by incorporating in the fuel that is fed to that engine a minor amount of an aliphatic organic compound of fluorine that is characterized by having a total of about 8 to about 30 carbon atoms, more often about 12 to 24 carbon atoms, there being a total of at least three fluorine atoms attached to either or both of the carbon atoms that are the terminal carbon atom of an aliphatic chain and the carbon atom immediately adjacent thereto. Thus all of the required minimum of three fluorine atoms can be on the terminal carbon atom, or two fluorine atoms can be attached to one carbon atom and the remaining one attached to the other carbon atom. The aliphatic group can be straight chain or somewhat branched.

Also included are such fluorine compounds that additionally have a polar group attached to another terminal aliphatic carbon atom, the polar group being a primary, secondary or tertiary amine group or an amine salt group. The salt will be that of the amine and a C to C carboxylic acid or of hydrogen chloride.

It is believed that the improvement in air/fuel ratio distribution obtained when practicing this invention results from a phenomenon wherein at least a portion of the additive becomes adsorbed on the walls of the intake system of the engine to create a surface which is not easily wetted by liquid drops of gasoline. Thus any drops of gasoline that fall out of the mixture of gasoline and air in the intake system do not spread into a film but remain as discrete drops, so that they are more easily re-entrained in the air stream passing through the manifold.

Among the fluorinated compounds that can be used in this invention are included those that are perfluorinated, i.e., those in which at least all the hydrogen atoms except one have been replaced by fluorine atoms and the remaining hydrogen atom has been replaced either by fluorine atom or by a polar group. The polar group can be an amino group or an amine salt group. Specific examples of suitable fluorinated compounds include perfluoro tributyl amine; perfluoro kerosene; l, l l -trifluoro octadecane; l, l l ,2,2,3,3-heptafluoro eicosane; perfluoro cetyl amine; l,l,2-trifluoro tetradecane; perfluoro 2-methyl dodecane; the acetic acid salt of l,l,l,2,2,3-hexafluoro stearyl amine; perfluoro octadecane; 1,1,1 ,2,l5,l6,16,l6-octafluoro cetane; the stearic acid salt of perfluoro dihexyl amine; and the butyric acid salt of 12,12,12-trifluoro dodecyl amine. Although the perfluoro compounds are the most effective from the standpoint of providing a surface that is not wetted by gasoline, there are instances in which it will be desirable to keep the fluorine content at a minimum commensurate with obtaining optimum non-wetting properties.

The fluorinated compounds of the invention will be incorporated in gasoline compositions in an amount ranging from about 1 to about 60 pounds per thousand barrels (ptb) of gasoline, one barrel containing 42 U5. gallons. More usually the fluorinated compounds will be used in concentrations of about 2 to 25 ptb. A concentration of one pound per thousand barrels of gasoline is roughly equal to about 4 parts per million; thus a range of from 1 to 60 ptb is about 0.0004 to about 0.024 percent by weight.

The gasolines in which the additives of this invention are employed are conventional petroleum distillate fuels boiling in the gasoline range and'intended for internal combustion engines, preferably spark ignition engines. Gasoline is defined as a mixture of liquid hydrocarbons having an initial boiling point somewhere in the range of about to F. and a final boiling point somewhere in the range of about 250 to 450F. Gasolines are supplied in a number of different grades, depending upon the type of service for which they are intended. The additives of the invention are particularly useful in motor and aviation gasolines. Motor gasolines include those defined by ASTM specification D- 439-58T, Types A, B and C, and are composed of a mixture of various types of hydrocarbons, including aromatics, olefins, paraffins, isoparaffins, naphthenes, and occasionally, diolefins. Not all of these types of hydrocarbons will necessarily be present in any particular gasoline. These fuels are derived from petroleum crude oil by various refining processes, including fractional distillation, catalytic cracking, hydroforming, alkylation, isomerization, polymerization and solvent extraction. Motor gasolines normally have boiling ranges within the limits of about 70F. and about 450F., while aviation gasolines have narrower boiling ranges, within the limits of about 100F. and 330F. The vapor pressures of gasoline as determined by ASTM Method D-323 vary between about 5 and about 18 psi at 100F. The properties of aviation gasolines are set forth in US. Military Specification MlL-F-5572 and ASTM Specification D-9lO-57T.

The additives employed in accordance with this invention can be used in gasolines with other additive agents conventionally used in such fuels. It has been common practice to employ from about 0.5 to about 4.0 cc./gal. of alkyl lead antiknock agents, such as tetraethyl lead, tetramethyl lead, dimethyl diethyl lead, or a similar alkyl lead antiknock agent or olefinic lead antiknock agent such as tetravinyl lead, triethyl vinyl lead, and the like, or a combination thereof, in motor gasolines and in aviation gasolines, e.g., 1.0 to 3.0 cc. of a tetraethyl-lead tetramethyl-lead combination. The lead compounds are customarily employed in conjunction with a scavenging agent such as ethylene dichloride or ethylene dibromide. Antiknock agents that can be used also include other organo-metallic additives containing lead, iron, nickel, lithium, manganese and the like. The effectiveness of the fluorine compounds of this invention does not depend on the presence of these or other antiknock agents, however. Other additives conventionally employed in gasolines may be used in practicing the present invention. These include corrosion inhibitors, rust inhibitors, antioxidants, solvent oils, antistatic agents, octane appreciators, e.g., t-butyl acetate, auxiliary scavengers like tri-B-chloroethyl phosphate, dyes, anti-icing agents, e.g., isopropanol, hexylene glycol, and the like. There may also be included certain oil-soluble dispersants and detergents to provide significant improvement in overall engine cleanliness. This is taught, for example, by Calvino et al in US. Pat. No. 3,223,495.

The nature of this invention and the advantages accruing from the practice thereof will be better understood when reference is made to the following examples, which include a preferred embodiment.

EXAMPLE 1 Gasoline blends were prepared using as the base an unleaded gasoline of 97 Research octane rating that had an initial boiling point of 97F, a 50 percent boiling point of 230F., and a final boiling point of 386F., by ASTM distillation method D-86. The gasoline blends were prepared by adding to the gasoline, by simple mixing, in one case perfluoro kerosene, and in another case perfluoro tributyl amine, the concentration in each instance being pounds per thousand barrels of gasoline. Each gasoline blend was then used as the fuel to operate a one-cylinder Wisconsin gasoline engine which was run at 1800 rpm for 14 hours. The Wisconsin engine is an L-head engine in which the fuel is mixed with air in a carburetor. The engine was equipped with a removable intake manifold. During the test the temperature of the air/fuel mixture in the manifold and the temperature of the intake air were controlled at 1 15F. and F. respectively so as to simulate typical intake conditions. From previous experience it was found that a 14-hour test period was sufficient to enable the additive in the gasoline to reach equilibrium adsorption levels on the surfaces of the intake manifold. At the end of the test, the intake manifold was removed from the engine and tested for nonwetting properties. The test consisted in placing six separate drops of gasoline on different areas of the manifold surface and then measuring the average diameter of the areas over which the gasoline spread on the surface. A similar test was run on an intake manifold from the Wisconsin engine test in which no additive had been incorporated in the base gasoline. In each instance the diameter was measured to the nearest onequarter inch. The results were as follows:

TABLE I Average Diameter Spread, inches No additive 2O ptb of perfluoro kerosene It will be seen that in the tests wherein the engine had been run with the gasoline containing either of the fluorine components, the intake manifold surfaces had been rendered more resistant to wetting by gasoline than had the manifold surfaces of the engine run with the gasoline containing no added fluorine compound. Based on a large number of tests, it has been determined that there is a good correlation between the results of the above-described Wisconsin engine test and a tendency for car hesitation on acceleration under actual driving conditions. When there is a wide spread between the air/fuel ratios reaching the several cylinders of an automotive engine and/or when there is a wide variation of air/fuel ratio with respect to time for particular cylinders, there will be a tendency for hesitation or even actual stalling when attempting to accelerate from a standing position, as for example when attempting to enter a stream of fast-moving traffic from a side street. The perfluoro kerosene used in the above tests had a fluorine content of 74.8 wt. percent, a carbon content of 25.14 wt. percent, and less than 0.03 percent hydrogen. It had a distillation range of from 1 15C. to 250C. (equals about 240F. to about 480F.).

it is to be understood that this invention is not to be limited to the specific examples herein presented by way of illustration. The scope of the invention is to be determined by the appended claims.

What is claimed is:

l. A gasoline composition comprising a major proportion of gasoline into which has been incorporated from about 1 to 60 pounds, per thousand barrels of the gasoline, of a fluorinated aliphatic hydrocarbon, fluorinated aliphatic hydrocarbyl amine, or fatty acid salt of a fluorinated aliphatic hydrocarbyl amine, said fluorinated compound having a total of from about 8 to 30 carbon atoms, there being a total of at least three fluowherein said fluorine compound comprises perfluorinated kerosene.

5. Gasoline composition as defined by claim 1 wherein said fluorine compound is perfluoro tributyl amine.

6. The method of improving the operation of an internal combustion engine which comprises running said engine with the gasoline composition defined by claim 1. 

2. Gasoline composition as defined by claim 1 wherein said fluorine compound is a perfluoro compound.
 3. Gasoline composition as defined by claim 1 wherein the fluorine compound has a total of from about 12 to about 24 carbon atoms.
 4. Gasoline composition as defined by claim 1 wherein said fluorine compound comprises perfluorinated kerosEne.
 5. Gasoline composition as defined by claim 1 wherein said fluorine compound is perfluoro tributyl amine.
 6. The method of improving the operation of an internal combustion engine which comprises running said engine with the gasoline composition defined by claim
 1. 